This invention generally relates to holsters for carrying portable wireless devices. More specifically, this invention relates to a two piece spring system for a cellular telephone holster.
As cellular telephones and other portable, wireless communication devices become smaller and smaller, more and more users choose to carry the devices by fastening them to a holster that is somehow attached to the user""s person. The holster has a clip that allows the holster to be attached to a persons belt.
When the holster and phone are attached to a person""s belt, the position of the phone may restrict a person""s movement. For example, when the person sits, the phone can undesirably protrude into the person""s waist. Therefore, prior art clips of cellular telephone holsters contained a mechanism to allow the clip to rotate with respect to the holster so that a person can adjust the phone position.
FIG. 1 shows a portion of a back side of a prior art cellular telephone holster 100. The holster 100 has a holster section 102 and a clip portion 104. The clip portion 104 has protrusions 106 formed to accept a pin (not shown) so that a clip (not shown) can be pivotably attached to the pin. A force applied to the clip causes the clip to open so that the holster 100 can be attached, for example, to the user""s belt. A spring (not shown) forces the clip to rest in the closed position when no force is applied to the clip.
The clip portion 104 is formed to have a circular opening 108 with a plurality of detents 114. The holster section 102 is formed to have protrusions 110, an a single, stainless steel leaf spring 112 is insertable between the protrusions 110. In normal assembly, a cap (not shown) is ultrasonic welded to the protrusions 110 to cover the leaf spring 112 assembly, and a clip (not shown) is attached to the clip portion 104. The cap and clip are not shown so as to reveal the leaf spring 112.
When a user applies a sufficient rotating force upon the holster section 100, that causes the holster section 100 to rotate with respect to the clip portion 104. A top portion 116 is forced downward against a bottom portion 118 of the leaf spring as the tip of the top portion 116 contacts one of the protrusions 120 formed by the plurality of detents 114, thereby forcing the bottom portion 118 to compress. When the tip of the top portion 116 comes into contact with another detent of the plurality of detents 114, the bottom portion 118 of the leaf spring 112 expands, and the pressure applied to the top portion 116 against the detent is causes the holster section 102 to remain in the new, rotated position relative to the clip portion 104.
The prior art leaf spring 112 is composed of a metal material such as stainless steel. Moreover, the leaf spring 112 is a single piece of metal material. Accelerated life testing of the leaf spring 112 produces tiny fractures in the metal material which indicates that after a user rotates the prior art holster 100 many times, the spring system may stop working and not hold the holster section 102 in a rotated position. Specifically, the prior art leaf spring 112 receives high stresses in its two corners (area with smallest radii); these stresses exceed the yield strength of the material (stainless steel 410).
In addition, the prior art leaf spring 112 does not provide enough spring force (which equates to turning resistance or torque); it provides only 0.58-1.0 in-lbs of torque. Therefore, what is needed is a reliable, cost effective spring system that allows reliable rotation of cellular telephone coupled to a holster.